Many packaging applications require the use of packaging materials, especially flexible packaging materials, that can be used to package food or non-food articles and protect these articles, during storage and distribution. Abuse resistance is thus often an important feature of the packaging material. Another property often desirable for such materials is heat shrinkability. In heat shrink packaging, an article is wrapped with a heat shrinkable polymeric film, typically a thermoplastic. The packaging material can be in the form of a bag, pouch, sheet folded in two ("centerfold film") or the like. The container formed by the film is loaded with the article to be packaged, and the film is then typically heat sealed (by constant heat type sealing or by impulse type sealing) or clip sealed along one or more edges of the film or bag to create a closed (hermetic or non-hermetic) package, followed by heat shrinking (e.g. by exposure to hot air or hot water) to provide a tight package. Heat shrinking not only adds aesthetic appeal; it also permits the packaging of articles with irregular shapes.
Film technology has progressed to the point where many films offer a high degree of abuse resistance and heat shrinkability. Examples include heat shrinkable films supplied by the Cryovac Division of W.R. Grace & Co.-Conn. These include D-955.TM., MPD-2055.TM., BDF-2001.TM., and other bag and film products.
Unfortunately, the same properties of toughness and abuse resistance that are desirable for the performance of the packaging material in protecting the contained article, often makes it difficult for the end user to open the package.
Various solutions to this problem have been proposed with a view to overcoming this problem and making it easier to open packages, especially heat shrunk packages, of the type just described.
One proposal calls for a line of perforations in a specific part of the film so that the package can be opened by tearing along the perforated line. This proposal suffers from the inherent weakening of the packaging material that occurs when a line of perforations is made in the film. If the film is a heat shrink film, the perforations can grow in size upon heat treatment of the film, and contaminants can potentially get into the package through the holes. This of course could reduce or totally negate the commercial value of the contents.
Another proposal has been to make a U-shaped hole in a specified location on the film, and then attach a paper seal over the hole to form a seal label that serves as an aid in opening the package. The disadvantage of this approach is that it requires a special apparatus for opening the U-shaped hole. The use of paper seals also adds to the production costs.
Still another proposal has been to attach an "opening tape" to the package. This is inherently cumbersome, and again adds cost to the package.
For certain equipment applications where flexible packaging film, especially heat shrink film, is used frequently, these proposals are extremely difficult to apply. This includes L-type sealer packaging machines which use centerfold film.
It would therefore be of great benefit to the packaging industry to provide a method of making an easy open package wherein the method is very compatible with current packaging systems, and makes use of currently available packaging films, but without the drawbacks of past proposed solutions to this problem.